Thermostatic circuit closer



.lune 5, 1923. v 1,457,376

A. LUDI THERMOSTATIC CIRCUIT CLOSER Filed J'uly 14 1921 e /f/u/m//n/ 45 EN. -f 2 Walz/0f: d@ in www Patented June 5, 19u23.

UNITED STATES PATENT OFFICE.

ADOLF LUDI, OF GRENCHEN, SWITZERLAND.

THERMOSTATIC CIRCUIT CLOSER.

Application led July 14, 1921. Serial No. 484,791.

To all whom t may concern:

Be it known that I, ADOLF LUDI, a citizen of Switzerland, and residing at Grenchen, Canton of Solothurn, Switzerland, have invented certain new and useful Improvements in Thermostatic Circuit Closers, of which the following is a specification.

The present invention relates to a thermostatic circuit closer as used for vulcanizing apparatus of the, kind where a spring eii'ects the open position of a contact lever.

The novel feature of the invention resides in a thermostatic bar which in its cold state maintains the contacting position yof the lever, but will cause the open position of the lever after a certain time when said bar gets bent by'the heat of an electrical resistance.

The annexed drawing shows one example of the device as applied to a vulcanizing apparatus.

Fig. l is a plan,

Fig. 2 a cross section and Figs. 3 to 7 .relate to details 'and Fig. 8 is a diagram of the electrical connections.

In a vulcanizing apparatus according to Figs. 1 to 8 the coverI 1 of the upper press plate 3 shows a recess inwhich 1s inserted an electrical resistance 2. This cover serves as bed platev of the whole apparatus and 'is cast in one piece with a channel-shaped hood 4 open at both ends having a shoulder 7 inside of this hood and with a casing 6 having aremovable cover plate 5. A bar 8 composed of two parallel metal strips soldered one above the other and having a different coeiiicient oi expansion is screwed fast with lone end by a screw 9 onto the shoulder 7 and carries at its other end which is rejecting into the casing 6 a stud 10. This stud penetrates into a slot 12 provided within a gudgeon 11 fast `on the wall of the casing and projects not only to the outside of the cylindrical surface of said stud, but also outside of a sleeve 14, so that a-iiat spring 15 fixed to an. arm 13 which is mounted ri idly on said sleeve and rotatably with t e same on, gudgeon 11 will rest with its sharp edge against said stud 10, which fact will prevent said arm 13.

f from being swung upwards under the eiect of the helical spring 16 interposed between Jcover and lever. t

In order to have arm 13 freely oscillating within certain limits the sleeve 14 is provided with a slot for the stud 10. The contact of'arm 13 with contact screw 25, 22, 21 is obtained by a strip 17 which is electrically insulated. from the arm and xed to it and is electrically connected to a terminal-19 of a source of electrical current by a conductor 18 passing through the wall of casing 6. The other terminal 20 of the source of electrical current connects to one end of the plate resistance 3, the other end kof which Lconnects with an insulated screw 21. This screw by means of a resilient contact strip., 22 and a knob 25 attached to it willcome into contact with a knob 24 provided on `strip 17. 'Plate resistance 3 is,l completely surrounded by insulating sheets of mica so as to have 4nocurrent in the casing and plates. A usher 23 guided within cover 5 is provide above the place of coupling between strip 17 and arm 13 and a stop pin 29 is fixed to cover plate 1 underneath arm 13 in order to prevent too great'a 'compression of' springs 16 and 22, when the pusher is `depressed in order to establish the contact position between strip 17 and the resilient strip 22.

The working of the thermostatie circuit closer isobtained byheating the plate resistance 2 by an electric current comin in at the terminals 19, 20. The bar 8 wil be heated with the# whole yapparatus vand as the metallic strip of greater dilatation is onI 'the upside ofthe bar, this bar will bend downwards whengetting het. Stud l() will begin to'sink and at the very moment, when spring 15 has lost its catch on said stud, the

farm '13 will snap upwards under the effect of spring '16, thus breaking suddenly the contact at 24, 25 and stopping theheating and vulcanizing process.

v In order to havefsome regulating means of the time of heating of the apparatus an axle 30 journalled within the walls of hood 4 is arranged underneath the bar 8 between casing 6 and shoulder 7, said axle bearing with an eccentric26 against the bar, so as to have the bar'and with it the stud 10 lowered or raised toQsome small amount, whenever the axle is turning, and to accelerate or retard the withdrawal of said stud from its contact with the iiat spring 15.

'An index' 31 is mounted on the axis and a Vstoppin This index indicates ona graduation 28 propin 27 for limiting the y,move-v ment of t is lever is fixed on the plate `1.

vided on the outside Vwall 'of hood 4 the amount of turn given to the axle 30 when adjusting the working of the bar 8.

What I claim as new, and desire to secure by Letters Patent, is:

1. A thermostatic circuit closer comprising a stationary contact, a slotted gudgeon,

a contact arm of a switch sleeved with a slotted end on said gudgeon a pusher for moving the contact arm to'contacting position, a spring resting against said arm biasing it to open position, a bar compounded of two parallel metal strips of diferent coeicient of expansion passing close to said slotted sleeve and kept fast at one end so as to bend, When getting heated, a stud fixed t0 the free end of said bar, traversing the slotted 4gudgeon and the slotted sleeve. and projecting beyond the sleeve, and a flat spring fast to said arm resting with a sharp edge against the projecting end of the stud, but left free at the Withdrawal of the same by the bending bar, and adapted to slip over the replaced stud when the arm is brought back again by said pusher into its contacting position.

2. A thermostatic circuit closer comprising a slotted gudgeon, a contact arm of a switch sleeved with a slotted end on said gudgcon, a pusher for moving the contact arm to contacting position, a spring biasing it to open position, a compound bar having two metai strips of dilerent coecient oit' expansion and arranged so as to bend when getting heated, a stud fixed to said bar and traversing the slotted gudgeon and the slotted sleeve of the arm, a fiat spring fast to said arm and catching with a sharp edge the projecting end of the stud in the contact position of the switch, and means for regulating the amount of catch between stud and flat spring and thereby the time of tripping of the switch.

3. A thermostatic circuit closer comprising a slotted gudgeon, a switch arm arranged rotatably With a sleeved and slotted end on said gudgeon, a compound bar adapted to bend when getting heated, a stud fixed to said bar and traversing'said gudgeon and said slotted sleeve, a fiat spring fast to said arm and catching the projecting end of the stud in the contact position of the arm, and means for regulating said catch, comprising, a journalled axle arranged in contact underneath the bar, an eccentric pro* vided thereon allowing to regulate the bend ot the same, a handle and an index on the outside of the casing adapted to indicate the position of the eccentric.

In testimony whereof I affix my signature in presence of two Witnesses.

ADOLF LUDI. `Witnessesz R. HEINGARTNER, L. M. HERMANN. 

